In internal combustion engines operating under normal and severe conditions, oil-insoluble particles can form from combustion and lubricant or fuel oxidation by-products. The oxidation products result from the high temperatures and the presence of metals which promote oxidation of the lubricant or fuel. Although antioxidants can prevent the fuel or lubricant from undergoing oxidation, antioxidants are not always fully effective and oxidation by-products are not the only source of contamination. Thus, dispersant and detergent additives are needed which disperse particulate matter and keep metal surfaces clean and free of deposits.
Dispersants are compositions which can facilitate the suspension of fine solid particles to inhibit the agglomeration and accumulation of the particles and their settling out in the fluid. Dispersants may actually break up particle agglomerations and suspend them in the fluid preventing the insoluble matter from forming deposits which will adhere to hot metal parts. Lubricating oils and fuels require dispersants and detergents to reduce or prevent these deposits from forming on internal combustion engine parts and to maintain engine cleanliness.
Alkenyl succinimides are known ashless dispersants for lubricants. It would be desirable to enhance the additive effectiveness of the alkenyl succinimides by giving them antiwear properties.
U.S. Pat. No. 4,584,114 describes ester-aminomercaptothiadiazole adducts as friction reducing and corrosion inhibiting additives for lubricants. Acids from which the esters are derived include succinic acid.
In U.S. Pat. No. 4,301,019 a reaction product of aminomercaptothiadiazole and a hydroxyl-containing unsaturated ester is described as a lubricant additive.
In U.S. Pat. No. 4,846,984 a reaction product of an aminomercaptothiadiazole and a hydrocarbyl epoxide is described as an antiwear and antioxidant enhancing additive for lubricants.
U.S. Pat. No. 2,760,933 discloses a carboxylic ester of a dimercaptothiadiazole as a corrosion inhibitor for lubricating oils.
None of these patents describe the reaction products of the instant invention.